Machines, such as off-road machines, on-road machines, motor graders, dozers, trucks, and the like are used in mining, construction, agriculture, petroleum, and other such applications. During operation an engine of the machine may be relied upon to produce a variable amount of power used by the machine implements to perform the task at hand, and to propel the machine in a direction of travel. In one non-limiting example, the machines may be equipped with an engine that utilizes more than one type of fuel. One such type of multi-fuel engine is a dual fuel internal combustion engine configured to use a combination of liquid diesel fuel and natural gas. In a dual fuel engine a small amount of liquid diesel fuel may be supplied for an ignition pilot which ignites a larger quantity of natural gas that supplies the main fuel source to the dual fuel engine. During operation, the machine may be required to traverse across a variety of terrain such as traveling up and down the steep grades of an access road that leads into and out of a mine or quarry. During the descent period the machine may be propelled down the steep grade by gravity (i.e., motoring condition). As a result, the dual fuel engine may consume a reduced amount of liquid diesel fuel and/or natural gas fuel during the motoring condition. Alternatively, in some embodiments during motoring the dual fuel engine may not consume any liquid diesel fuel and/or natural gas. In such conditions, residual combustion gas and/or air may accumulate and/or backflow into one or more cylinders of the dual fuel engine due to the reduced amount of liquid diesel fuel injected into the pilot ignition. The accumulated combustion gas may leak into the diesel injector ignition pilot and cause an abnormal operation of the engine. For example, at the end of the motoring condition the machine may reach the bottom of its descent and the operator may attempt to slowly increase the load (i.e., increase the throttle or accelerator) on the dual fuel engine to maintain or increase the propulsion of the machine in the desired direction of travel. However, if a sufficient amount of combustion gas has accumulated in the diesel injection ignition pilot then the pilot ignition of the diesel fuel may not occur. This may cause an abnormal operation of the engine such as but not limited to, one or more cylinders to misfire, or other such engine malfunction. Such an abnormal operating condition of the engine may cause the machine to operate below optimal levels or in some cases may altogether cease operation of one or more of the cylinders of the machine.
A system for detecting a gaseous fuel leak in dual fuel engines is disclosed in International Patent Application Publication No. WO 2014/066995 entitled, “Method and System for Detecting and Diagnosing a Gaseous Fuel Leak in a Dual Fuel Internal Combustion Engine System,” (the '995 publication). The dual fuel engine disclosed therein is equipped with a fuel system for supplying a pilot fuel and a gaseous fuel to the dual fuel internal combustion engine. The fuel system of the '995 publication further includes a controller, a liquid fuel pressure sensor which monitors the pressure in the liquid fuel rail, and a gaseous fuel pressure sensor which monitors the pressure in the gaseous fuel rail. The controller receives the liquid fuel rail pressure and the gaseous fuel rail pressure and calculates the pressure differential between the two received pressures. The pressure differential between the liquid fuel rail and the gaseous fuel rail is maintained such that the liquid fuel is typically kept at a higher pressure to prevent gaseous fuel leakage into the fuel injector. Additionally, to monitor and detect a gaseous fuel leak in the fuel system, a return line pressure sensor is coupled to the liquid fuel return line of the fuel system and configured to continuously monitor the liquid fuel return line pressure. During engine operation, if the gaseous fuel pressure becomes higher than the liquid fuel pressure then gaseous fuel will leak into the liquid fuel within the fuel injector. As a result, an increase of gaseous fuel will be present in the liquid fuel return line and the pressure sensor will measure an increase in the pressure of the liquid fuel return line thereby indicating a gaseous leak in the fuel system.
While arguably effective for the detection of a gaseous fuel leak, the '995 publication does not monitor the individual cylinder pressure of each cylinder in the dual fuel engine to determine whether there is a gaseous fuel leak in the fuel system.